1. Field of the Invention
The present invention-relates to an ultrasonic observation system for ultrasonically observing an affected part in front of a part to be operated and, in particular, to an ultrasonic observation system used for extracting three-dimensional ultrasonic images in neurosurgery, for example.
2. Related Art Statement
Conventionally, in order to remove a tumor in a less invasive manner in neurosurgery, an endoscope has been often used.
In such a system, a treating apparatus is inserted to a treated part in the cranium while an operator watching an endoscope observation image in order to perform a treatment such as tumor removal. In this case, the endoscope is fixed and/or is supported by a medical equipment holding apparatus including multiple arms and joints. In the cranium, important tissue such as nerves and blood vessels are tangled complexly and minutely. Therefore, the holding apparatus needs to be able to move an endoscope minutely and smoothly so as not to hurt tissue and needs to be able to fix an endoscope at an accurate position.
A medical equipment holding apparatus disclosed in U.S. Pat. No. 2001/0,027,313A1 has been proposed as a system for holding and fixing an endoscope in order to perform such an operation.
In the medical equipment holding apparatus disclosed in U.S. Pat. No. 2001/0,027,313A1, an installing part is attached freely slidably at a side rail of an operating table. The installing part includes a link mechanism, which is a holding portion tilting mechanism, through a supporting arm, an upper supporting member, and a first parallel link mechanism. The holding portion in the link mechanism holds a rigid endoscope. With this construction, the first parallel link mechanism and the holding portion tilting mechanism arm are deformed without changing the position for installing the holding apparatus so as to change the direction of the rigid endoscope.
In the method for guiding a rigid endoscope toward a part to be operated, a part of the cranium is opened, and the treatment is then performed thereon blindly. In order to prevent this and to guide the rigid endoscope toward the part to be operated more securely, an in-operation X-ray observation apparatus or an in-operation ultrasonic observation apparatus is used as a measure for observing the distal end of the rigid endoscope in real time.
In general, when an ultrasonic observation apparatus is used, a part of the cranium is opened, and an ultrasonic probe incorporating an ultrasonic vibrator is then put on the surface of the brain so as to observe a part of the brain.
Such an ultrasonic observation apparatus is disclosed in U.S. Pat. No. 2003/0,045,768A1 and Unexamined Patent Application Publication No. 11-206764.
U.S. Pat. No. 2003/0,045,768A1 discloses an ultrasonic probe, which can be inserted to a part of a small opening. As shown in FIGS. 19 and 20, the sides and front of the inserting axis of the ultrasonic probe can be observed.
Unexamined Patent Application Publication No. 11-206764 discloses a so-called electronic scan type ultrasonic probe, which can observe the front part. According to the technology disclosed in the publication, the distal end of the ultrasonic probe is put on the surface of a living body such that an image several centimeters ahead from the surface of the living body can be observed.
In the ultrasonic observation, an operator observes a two-dimensional tomographic image (depth image) during an operation. Therefore, an ultrasonic probe is moved freely with respect to the head, and the rigid endoscope is guided to a part to be operated by checking a desired observed part.
Here, a two-dimensional tomographic image is observed in general ultrasonic observation. However, a three-dimensional image is desirably used for the observation in order to realize the accurate position and size of a tumor, for example. Therefore, the operator puts an ultrasonic probe on the brain surface, that is a part to be operated, during an operation and then moves the direction and/or position of the ultrasonic probe slightly. Thus, the operator observes two-dimensional images of the various conditions and then understands the various conditions as a three-dimensional image in his/her brain.
Unlike the conventional example in which an operator images a three-dimensional image from two-dimensional images in his/her brain as disclosed in Unexamined Patent Application Publication No. 11-206764, a conventional example in which a three-dimensional image can be obtained more easily has been proposed as disclosed in Unexamined Patent Application Publication No. 6-261900.
In an ultrasonic diagnosis apparatus disclosed in Unexamined Patent Application Publication No. 6-261900, at least one of a magnetic field generating means and a detecting means is positioned at the distal end of the ultrasonic probe, and a three-dimensional image forming means recognizes the relative position coordinates of the distal end or ultrasonic vibrator of the ultrasonic probe for the magnetic field generated by the magnetic field generating means based on a value detected by the detecting means. Then, the ultrasonic diagnosis apparatus forms a three-dimensional image by using a tomographic image of the ultrasonic probe and the recognized position coordinates while the operator is inserting and is retracting the ultrasonic probe by hand.
The three-dimensional-like state of the distal end of the endoscope may be required to recognize by using an ultrasonic probe for guiding the endoscope distal end as an observing unit to a part to be operated. In this case, according to the conventional technology, the distal end of an endoscope can be guided to a part to be operated securely by checking the movement continuously from the time immediately after the distal end is inserted to the head of a patient until the distal end reaches a part to be operated. In order to do so, the direction of a two-dimensional image imaged ultrasonically must substantially coincide with the plane including an inserting axis of the endoscope.
When an ultrasonic observation apparatus disclosed in U.S. Pat. No. 2003/0,045,768A1 and Unexamined Patent Application Publication No. 11-206764 is used in the cranial nerve field, the cranium is opened, and the ultrasonic probe must be put on the brain surface in order to obtain an image. In this case, from the operator's experience, the position of the ultrasonic probe is determined and is fixed, and then an endoscope is inserted thereto.
FIG. 30 is an explanatory diagram showing a positional relationship between the conventional endoscope and the ultrasonic probe.
As shown in FIG. 30, when a plane A0 including an inserting axis 502 of an endoscope 501 and a center axis 512 of an ultrasonic probe 511 is displaced from a two-dimensional plane (ultrasonic observation plane) B0 of an ultrasonic image rendered by the ultrasonic probe 511 by an angle α0, an endoscope distal end 503 does not appear on the ultrasonic image until the endoscope distal end 503 approaches the part to be operated.
On the other hand, in some operations, an ultrasonic probe may be inserted from an endoscope inserting hole, and the endoscope may be guided to a part to be operated while an operator checking the image information of the front of the endoscope. In this case, the operator inserts the ultrasonic probe as shown in U.S. Pat. No. 2003/0,045,768A1 and the endoscope alternately from the opening of the patient's head so as to access the part to be operated.